SB-650...RG-62U cable....

[Guy Giacopuzzi]

I happen to have found an SB-650 at a swap meet, and this last weekend I
tried to get it going....using a 303/401 combo...seemed to work ok on
the lower bands (80,40) but fell apart on the upper...in searching the
archives, I found Sandi Gerli had a similar problem back in 1999...did
some checking--swapped the IC-12,24 and 25 with known good ones--no
change.   Then I found the HFO voltage fell significantly when I plugged
the cable--RG 58, not RG 62U--into the 401'...when the cable was
disconnected, I found the 650' read all frequencies thru 10
meters...connect the cable and it only read 80 and 40.  Could the RG 58
be loading the HFO in the 303 excessively?   Found some RG-62u cable
with RCA connectors...no improvement.  When I put an RF probe on the HFO
output of the 303', I found about 1.3 volts rf (neg DC) and the 650'
reads all frequencies, 10 thru 80.  When I connected the cable to the
401' it drops to about 0.6 volts and the 650' won't read from 20 meters
on up thru 10...my conclusion is that the HFO amplifier in the 650 isn't
doing it's job...before I order the two transistors, does anyone have
any further input?

guy g. giacopuzzi, WA6OQQ

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